Electron discharge device



July 16, 1946.

H- J- DAILEY ETAL ELECTRON DISCHARGE DEVICE Fild Oct. 12, 1944 INVENTORS4 1? EWE E Patented July 16, 1946 ELECTRON DISCHARGE DEVICE Hampton J.Bailey and Leo 0. Werner, Bloomfield,

N. J., assignors to Westinghouse Electric Corporation, East Pittsburgh,Pa., a corporation of Pennsylvania Application October 12, 1944, SerialNo. 558,300

6 Claims. 1

This invention relates to electron discharge devices and particularly tospacers therein for the filament leads which have, of necessity, closerelation to the grid or its supports and are subject to a high frequencyfield between filament and grid. The invention is an improvement uponsole application of inventor Hampton J. Dailey herein, whose applicationSerial No. 509,649 was filed in the United States Patent Oifice November10, 1943 and assigned to the sa e assignee as the present jointinvention.

In its general aspect, the present invention has for. an object greatersecurity against possible efiects of a high frequency field creating ashorting path to the filament lead from the grid lead nearest thereto.

More specifically, an object of the invention is to imbed the insulatingspacer in a metallic spacer for maximum protection against exposure ofthe insulating spacer to the high frequency field.

Another object of the invention is to avoid presence of conductiveconnections in contact with the insulators and having an edge exposuretoward the most adjacent part of the grid.

Still further objects of the inventionrwill appear to those skilled inthe art to which it appertains as the description progresses, both bydirect reference thereto and by implication from the context.

Referring to the accompanying drawing in which like numerals ofreference indicate similar parts throughout the several views;

Figure 1 is an elevational section of an electron discharge deviceembodying the present invention;

Figure 2 is a plan of the spacer member with the filament lead-in wireso posts and taken as a section on line II-II of Fig. 3;

Figure 3 is a sectional view on line IlI--III of Fig. 2;

Figure 4 is a perspective view of one of the spacer members; and tFigure 5 is a perspective view of one of the insulators.

In the specific embodiment of the invention illustrated in said drawing,the general organization of the electron discharge device provides avacuum tight container formed by an outer metal tube In which acts asthe anode and which is closed at its upper end as usual and closed atits lower end by means of a glass bowl or base [2 which is sealed to itin suitable manner as by a feather-edge joint l3. From the bottom of thebowl, at the exterior thereof, project the usual prongs [4 for makingconnection with the internal electrodes.

Coaxially within the anode is a grid 15, and insidethe grid is a cathodel6 formed as a plurality of hairpin sections each with parallel wires orlegs and all said legs symmetrically disposed in cylindrical arrangementrelatively close proximity to the grid. On the axis of the coaxialelectrodes is a metallic post H which constitutes a center support forthe upper end of the cathode. Each filament section has one leg securedat its lower end to a post 20 and the other leg secured at its lower endto a similar post 2|, the several posts extending downwardly into thebowl l2. All posts constituting one set pass through in contact with andare secured in a metallic supporting plate 22 forming a commonelectrical connection thereto and the other set pass with clearancethrough said plate and are secured to an insulative plate 23 juxtaposedat the under side of said metallic supporting plate, the posts 20 beingsecured to brackets 24 which support the two plates thereabove. Thesebrackets are carried by inwardly projecting parts of a plurality of theaforementioned prongs l4 and thereby have electrical connection to theexterior. Said metallic supporting plate 22 has connection 25 to anotherone of said prongs. Of course one set of posts will be at a considerablyhigher potential than the other set for obtaining current flow in theseveral filament sections.

Intermediate the ends of the several posts 20 and 2| and also on thecentral post I! is a transverse and preferably circular spacer 26. Thegrid supporting wires or legs 21 pass to the bowl at the outside of thespacer out of contact therefrom, but because of limited space,necessarily near to the same and likewise near to the filament parts.There is a high electrical gradient or radio frequency electrostaticfield between the posts of one set and the grid. While said spacer inthe sole application referred to above substituted metal for the priorart insulating spacer, for counteracting the electrostatic field, thepresent invention not only utilizes the metal spacer, but gives addedprotection against discharge of the electrostatic field across thesurface of the ceramic and avoids projections and other structure whichmight tend to promote shorting of the high frequency across or throughthe ceramic.

According to the present invention, the metal spacer is shown as a pairof juxtaposed substantially flat sections 28, 29 each having registeringstepped recesses 30 therethrough, of which the larger parts of therecesses are at the juxtaposed faces of the sections and the smallerparts of the recesses are toward the exposed faces of said sections.Thus, when the sections are assembled, the registering larger parts ofsaid recesses form pockets, and in each such pocket is located a ceramicdisc 3| of substantially the same size, shape and dimensions as thepocket so asto be retained in the pocket merely by virtue of inclusionthere'- in with a portion of the section around the recess overlappingthe edge of the disc, and by retention of said spacer sections fromseparating. By utilization of ceramic discs SI of slightly greaterthickness than the depth of the pockets, said discs may be rigidly heldby clamping the spacer sections toward each other. Each said disc 3| hasa central hole 32 therethrough for the filament post and substantiallythe same diameter as said post.

Both support andclainp-ing of the sections 28,

28 constituting the spacer 26 are obtained by studs 33 perpendicular toand between said metallic spacer 25 and metallic supporting plate 22.Screws as extending through holes at in said spacer and in saidsupporting plates threading into opposite ends of the studs clamp theseveral parts together as a rigid structure, the lower screws preferablyalso passing through the insulative plate 23 and clamping it to thesupporting plate.

It may now be observed that the ceramic discs or insulators are ineffect embedded in the metallic spacer so that exposed surfaces of saidinsulators are offset inwardly from, the flat exposed surfaces of thesaid spacer. Thus the insulators are removed from the high frequencyfield in their entirety and cannot form any part of a shorting paththerefor to the filament post either across a surface of the insulatoror through the body of the insulator. Furthermore, support for thespacer is obtained by studs which are further from the grid wires thanthe filament posts, and no slip coils are required or are present on thefilament posts either to retain the insulators or to position thespacer. This has the beneficial effector, avoiding any projections onthe filament posts which might tend to lower the space resistance toshorting of high frequency from the grid to the filament.

We claim:

1. An electron discharge device having a grid and a cathode within thegrid, a spacer transverse to a part of said cathode and in proximity toa part of said grid, and an insulator in said spacer embedded inwardlyof exposed surfaces of said spacer.

2. A spacer for filament posts comprising a metallic flat structurehaving a recess therethrough,

and an insulator within said recess with a part of the recess above andbelow said insulator.

3. A spacer for filament posts comprising a metallic flat structurehaving top and bottom faces, and having a recess extending through saidstructure from one of said faces to the other, said recess beingenlarged intermediate its ends, and an insulator in the enlarged part ofsaid recess.

4. A spacer for filament posts comprising a pair of juxtaposed sectionshavingv registering recesses therethrough, the juxtaposed part of saidrecesses of the two sections being of greater diameter than the parts ofsaid recesses most remote from each other, and an insulator includedbetween said sections in the. said parts of said recesses of greaterdiameter.

5. A spacer for filament posts comprising a pair of juxtaposed metallicsections having registering recesses therethrough, an insulative disc insaid recesses and overlapped by parts. of said metallic sections, andmeans for clamping sdid sections together and retaining said disc insaid recesses.

-6. A spacer for filament post-s comprising a pair of juxtaposedmetallic sections having stepped recesses therethrough, the largerportion of the recesses being next the juxtaposed surfaces of the saidsections, and insulative disc in said larger portion and larger than thesmaller portion of the stepped recesses, and means holding said sectionsassembled and the discs retained in the said recesses.

HAMPTON J. DAILEY. LEO c. WERNER.

